Preheat your oven to 350°F (175°C). Line an 8x8 inch square baking pan with parchment paper, leaving an overhang on the sides for easy removal later.

In a large mixing bowl, combine the granulated sugar and fresh lemon zest. Use your fingertips to massage the zest into the sugar until it is fragrant and resembles wet sand. This releases the oils and maximizes the lemon flavor.

Pour the melted (and slightly cooled) butter into the lemon sugar. Whisk until well combined. Add the eggs, lemon juice, and vanilla extract, whisking vigorously until the mixture is smooth and slightly pale.

Sprinkle the all-purpose flour and salt over the wet mixture. Use a rubber spatula to gently fold the ingredients together until just combined. Be careful not to overmix!

Gently fold in the raspberries, taking care not to crush them too much. If using frozen berries, toss them in a teaspoon of flour first to prevent sinking.

Pour the batter into your prepared pan and smooth the top. Bake for 30-35 minutes, or until the edges are golden brown and a toothpick inserted into the center comes out with moist crumbs.

Let the blondies cool entirely in the pan on a wire rack. They will continue to set as they cool.

While the blondies cool, whisk together the powdered sugar, a splash of lemon juice, and a spoonful of raspberry jam until you reach a smooth, pourable consistency.

Once the blondies are completely cool, lift them out of the pan using the parchment paper overhang. Drizzle the sweet glaze generously over the top, slice into squares, and enjoy!